Your bot will be configured to login to Rocket.Chat server with the designated bot username and password by using these credentials in the bot’s environment ROCKETCHAT_USER and ROCKETCHAT_PASSWORD

Note that for bots email, a common workaround to avoid creating multiple accounts is to use Gmail +addresses, e.g. youremail+botnam@gmail.com.
See this issue for more

Talk to your bot

Your bot will usually respond to all messages addressed directly to the bot user (depending on the particular bot framework).
i.e. Messages prepended with BOT_NAME or a preconfigured BOT_ALIAS.

If the bot is configured to listen on Direct Messages (RESPOND_TO_DM=true), the prepend is not necessary (it’s automatically added internally) so the bot should respond to all messages in the DM channel.